Tractor drawbar



June 8, 1943,

J. D. ROBERTSON TRACTOR DRAW BAR 3 Sheets-Shea! 1 Filed June :5, 1940 mw w. 1 w R m .J.

June 18435 J, D. RoRTsoN TRACTOR DRAW BAR Filed June :5, .1940 :5 Sheets-sheet 2 INVENTOR. Jack D. Robertson v fifi4,

AITQRNEY.

Emma EQQ-EQ J ROBERTSON 2,321,51

TRACTOR DRAW BAR Filed Juri s, 1940 sshms-sheet s I i5 1, {I

' \u I I o H 5 HIIH'II 1 v I ll ll k 4 :10 1

X I! I u l/ l/.// E 3 I x INVENTOR.

L; ATTORNEY.

Patented June 8,' 1943 -UNITE'DSTATES PATENT OFFICE.

TRACTOR DRAWBAR Jack D. Robertson, Balls, Tex., assignor of onehalf to Gilbert 0. Paudler, Crosbyton, Tex.

Application June 3, 1940, Serial No. 338,654

. Claims.

This invention relates to an improvement in draw bars for tractors, and more particularly to the type of draw bar used with automatic linkage systems for drawing implements attached to a tractor.

' Power driven tractors which have been used heretofore have been subject to the objecion that, when the implement attached thereto strikes an obstruction that prevents forward motion, the continued rotation of the rear wheels tends to cause the tractor to upset in somersault fashion, frequently injurying the driver and damaging the tractor and the equipment.

It has been proposed to avoid this objection by coupling the implement to the tractor through linkage which has provision through hydraulic mechanism for relieving the pressure on the tractor when the implement strikes an obstruction. The draw bar used heretofore with such linkage has not been constructed and arranged so as to operate the hydraulic mechanism effectively due to the high point of coupling of the implement therewith and the point of connection of the weight at or adjacent the level of the rear axle which prevented it from functioning in the desired manner.

The object of this invention is to improve the construction of the draw bar to provide for a lower point of connection of the implement with the tractor and more eilective actuation of the linkage by the draw bar to prevent overturning of the tractor. v

This is eifectively accomplished by locating the point of drafting force of the draw bar at or adjacent the level of the. rear axle, and applying a -force above the rear axle substantially equal the force applied below the axle, the draw bar being arranged in an upright position and having provision for attachment of the implement to the lower end portion thereof.

A preferred embodiment of the invention is illustrated in the accompanying drawings, in

which: r

Fig. 1 is a side elevation of a tractor and imple- 'ment utiliz ng the improved form of draw bar,

the tractor having a rear wheel removed;

Fig. 2 is a partial rear elevation thereof and partial sectionon the line 2-2 of Fig. 1;

. The invention is shown as applied to a power driven tractor having a linkage controlled hy-- draulic system which may be substantially of the character illustrated in Ferguson patent, No. 2,118,181, May 24, 1938. In such a system, the tractor is constructed with a power plant designated generally by the numeral I, having power driving connection with the rear axles of the tractor designated 2, upon which are mounted the rear wheels 3. The rear axles 2 extend.

through axle housings l. The tractor is provided with the usual front wheels 5.

Mounted within the tractor housing is a hydraulic power device 6 to which liquid is supplied under pressure from a pump within the tractor under control or" a valve actuated by a lever I which also has a manual control 8 connected therewith. The piston of the power device 6 has a connecting rod attachedto a cross shafts,

journaled in the tractor housing, to the outer ends of which arms In are attached.

Fig. 3 is a detached perspective view of the draw bar;

bar actuating means.

Attached to the undersides of the rear axle housings 4. are lugs ll, extending downwardly therefrom and having links I! pivotally supported by the lugs H and extending rearwardly therefrom. Intermediate the ends of the links l2 are connecting rods l3,pivoted thereto and to the upper ends of the arms III. A link H extends substantially parallel with the links l2 and has its front end pivotally connected with a rod 45 surrounded by a spring l6 interposed .between the rod l5 and the tractor housing tending to move said rod in a rearward direction. The rod i5 extends to and is connected with the lever I that controls the valve which regulates the admission of liquid to the power device 6 which moves the piston thereof rearwardly to raise upward on the arms "I and links l3, sub-* stantially in the manner described and set forth in the above-mentioned Ferguson patent, No. 2 1 1a,1s1.

Connected with the rear end portions of the links H and II is a draw bar designated generally by the numeral II which is shown in Figs. 2 and 3 as of substantially polygonal shape with outwardly bulging sides Ila extending upwardly from opposite ends of a connecting bar It which forms the base of the draw bar, and preferably being formed integral with the sides thereof,

which sides terminate in upturned ears Mb. The connecting bar l8 has a plurality of openings IQ therein for detachable connection with a clevis 20 attached to an implement, one form of which is shown generally at 2 I. The clevis may be connected selectively with any desired one of the holes I9 tovary the point of connection of the implement with the draw bar as may be desired.

The sides i'ia of the draw bar I! have a rod 22 extending transversely therethrough, the outer ends of which rod form pivotal connections with the links l2, which pivotal connections are dis posed at or adjacent the midpoint of the length of the draw bar- H. The rod 22 also extends through diagonal braces llc welded to the sides of the draw-bar frame, as shown in Fig. 3, and bracing the draw-bar and the rod. The upper end of the draw-bar i1 is pivotally connected by a pivot pin 23, passing through the ears "b, with the rearward end of the link H. The ratio of the distance between the pivots 22 and 23 and the pivots 22 and connecting bar 18 is substantially twelve to fourteen. It has been found by ex eriment that the pivots 22 and 23 should be spaced apart a distance of twelve inches, while the pivots 22 should be spaced fourteen inches from the connecting bar I8, for best results.

When the tractor is operated to draw forward the implement 2|, the operator first swings the lever 8 to the right in Figs. 1 and 5, which moves the valve lever I to open the control valve, al-' lowing the liquid to escape from the cylinder of the power device 6. The piston of said power device then moves inward under the influence of the weight of the draw bar H, which is thus permitted to move downward; The draft which is then imposed on the draw bar I'I, tends to turn it about the pivot rod 22. This movement is resisted by the spring l8 which is compressed by the link It moving to the right and thereby mov-- ing the lever I to close the control valve, and holding the draw bar H in its draft position. The force exerted downward by the arms .will apply a reaction to the tractor housing forwardly of the rear axles 2, such as will tend to hold the tractor in a level position with the forward end continuously resting on the ground.

This will also tend to increase the traction of the rear wheels with the ground, thereby preventing a backward upsetting of the tractor.

In this way, provision may be made for the operation of relatively heavy implements even by light weight tractors without danger of upsetting, and yet with full assurance of adequate draft for the implements. Provision is made also to raise and lower the draw bar automatically or when desired in the usual way, by the actuation of the hydraulic power device incorporated in the tractor.

I claim:

f 1. The combination with a tractor having a hydraulic power device therein and means for controlling the supply of fluid thereto, of a draw bar extending substantially in an upright direction rearwardly of the tractor and having means for connection with an implement adjacent the lower end portion thereof, and links pivotally connected with the draw bar intermediate the ends thereof and adjacent the upper end thereof respectively, one of said links being pivotally connected with the tractor and the other being operatively connected with the controlling means.

2. The combination with a tractor having a hydraulic power device therein and means for controlling the supply of fluid thereto, of a draw bar extending substantially in an upright direction rearwardly of the tractor, said draw bar having spaced upwardly extending sides with a connecting bar joining the lower portions of said sides, a link pivotally connected with the upper end portion of the draw bar and operatively connected with the controlling means, and links pivotally connected withthe sides of the draw bar and with the tractor.

3. The combination with a tractor having a hydraulic power device therein and means for controlling the supply of fluid thereto, of a draw bar extending substantiallyin an upright direc tion rearwardly of the tractor. said drawbar having spaced upwardly extending sides with a connecting bar joining the lower portions of said sides, a link pivotally connected withthe upper end portion of the draw barand operatively connected with the controlling means, and links pivotally connected with the sides of the draw bar. and with the tractor, the first-mentioned link having connection with the tractor above and forwardly o! the rear axles of the tractor and the last-mentioned links having connection with the tractor below the rear axles thereof.

4. In a tractor of the character having a structure withupper and lower links hinged thereto, a power device on the tractor having means connected with the loweklink for raising the same, and controlling means for the power device con- I nected with the upper link, the combination with said upper and lower links, of an upright draw bar for attaching an agricultural implement to the tractor, said draw bar having implement attaching means at the lower end portion thereof, means for pivotally connecting the upper end portion of the draw bar with the upper link, and

means for pivotally connecting the intermediate portion of the draw. bar with the lower link.

5. In a'tractorof the character having a structure with a pair of lower links hinged thereto in transversely spaced relation, an upper link hinged to the tractor structure, a hydraulic power device on the tractor having means connected with the lower links for raising the same,

and controlling means for the power device connected with the upper link, the combination with said upper and lower links, of an upri ht draw bar for attaching an agricultural implement to the tractor and having implement attaching means at the lower end portion thereof, means for pivotally connecting the upper end portion of the'draw bar with the upper link and a pivot rod extending transversely of the draw bar intermediate said end portions thereof and pivotally connecting said pair of lower links with the with the upper link, the combination with said upper and lower links, of an upright draw bar for attaching an agricultural implement to the tractor and having spaced upright sides with a connecting bar between the lower end portions thereof adapted for attachment to the implement, means for pivotally connecting the upper end portion of the draw bar with the upper link, and a pivot rod extending laterally from the upright sides intermediate the end portions there- I of and pivotally-connecting said lower links with the draw'bar.

7. In a tractor of the character having a structure with a pair of lower links hinged thereto in transversely spaced relation, an upper link hinged to the tractor structure, a hydraulic power device on the tractor having means connected nected with the pivot rod. erally from the upright sides intermediate the withthe lower links for raising the same, and 9. A draw bar adapted for attachment of an controlling means for the power device conagricultural implement to a tractor, said draw nected with the upper link, the combination bar comprising spaced upright sides converging with said upper-and lower links, of an upright toward their upper ends with a connecting bar draw bar for attaching an agricultural implebetween the lower end portions thereof for atment to-the tractor and having spaced upright tachment to the implement, said upright sides sides with a connectingbar between the lower having pivot means at the upper end portions end portions thereof adapted for attachment to thereof, and a pivot rod extending laterally from the implement, means for pivotally connecting the upright sides and carried thereby intermedithe upper end portion of the draw bar with the 10 ate the end portions thereof for connection with upper link, a pivot rod extending laterally from tractor attachments.

the upright sides intermediate the end portions 10. A draw bar adapted for attachment of an thereof and pivotally connecting said lower links agricultural implement to a tractor, said draw with the draw bar, and braces extending up- 'bar comprising spaced upright sides with a conwardly from oppositeends of the connecting bar 15 necting bar between the lower end portions to the upper ends of the upright sides and joined thereof for attachment to the implement, said thereto, the intermediate portions of said braces upright sides having pivot means at the upper being spaced from the upright sides and con- (and portions thereof, a pivot rod extending lat'- 8. A draw bar adapted for attachment of an 20 end portions thereof for connection with tractor agricultural implement to a tractor, said draw attachments, and braces extending upwardly barcomprising spaced upright sides with a confrom opposite ends of 'the connecting bar to necting bar between the lower end portions the upper ends of the upright sides and Joined thereof forattachment to the implement, said thereto, the intermediate portions of the braces upright sides having pivot means at the upper 5 being spaced from the upright sides and conend portions thereof, and a pivot rod extending nected with the pivot rod.

laterally from the upright sides intermediate the end portions thereof for connection with tractor JACK D. ROBERTSON. attachments. 

